Temperatures rise over 'inconsistencies' in UN climate change report
THE recent pause in average global surface temperature rises made lifting confidence in the extent of the human contribution to climate change "incomprehensible", a leading US climate scientist has said.
Judith Curry, chair of the School of Earth and Atmospheric Sciences at Georgia Institute of Technology, yesterday published her analysis of a leaked IPCC draft report that has sparked an international furore.
The leaked draft said it was "extremely likely" that human influence on climate caused more than half of the increase in global average surface temperature from 1951 to 2010.
The draft report said the world would continue to warm catastrophically unless there was drastic action to curb greenhouse gases.
Britain's Mail on Sunday said the draft report showed climate models, and the IPCC, had significantly overestimated the rate of global warming.
Australian climate scientists said the IPCC report had not yet been finalised.
But they said the revised warming figure of 0.12C a decade in the draft IPCC report was within the range quoted in the 2007 IPCC report of between 0.1C and 0.16C.
Britain's The Daily Mail said the IPCC had previously estimated warming at 0.2C a decade.
It has been widely acknowledged that climate models have consistently overstated the rise in global temperatures. A report published in Nature Climate Change last week said recent observed global warming had been less than half the rate simulated by climate models.
"By averaging simulated temperatures only at locations where corresponding observations exist, we find an average simulated rise in global mean surface temperature of 0.3 degrees Celsius per decade," the report said.
"The observed rate of warming given above is less than half of this simulated rate."
The paper said the observed trend between 1998 and 2012 suggested a temporary "hiatus" in global warming.
Several explanations have been offered to explain the pause, which is now widely acknowledged, including a take-up of heat in the deep oceans and the cooling effect of volcanoes and particulate emissions from increased coal burning in China, among others.
Australian climate scientists said the issues would be more thoroughly examined in the final IPCC report, which was due to be published on September 27.
Professor Curry said she believed there were inconsistencies in the draft report.
"If there are substantial changes in a conclusion in the AR5 (2013 report) relative to a confident conclusion in the AR4 (2007 report) then the confidence level should not increase and should probably drop, since the science clearly is not settled and is in a state of flux," Professor Curry said.
"An increase in confidence in the attribution statement, in view of the recent pause and the lower confidence level in some of the supporting findings, is incomprehensible to me.
"Further, the projections of 21st century changes remain overconfident."
Professor Curry said the draft report showed the IPCC process was having difficulty keeping up with the rapid pace of publication of scientific papers.
She recommended that the consensus-seeking IPCC process be abandoned in favour of a more traditional review. "I think that such a process would better support scientific progress and be more useful for policymakers."
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